单层α-MoO_(3)半导体薄膜的范德瓦耳斯外延制备  

Van der Waals Epitaxial Preparation of Single-Layerα-MoO_(3)Semiconductor Thin Films

作　　者：韩钰 牛群 周琴 赵爱迪 HAN Yu;NIU Qun;ZHOU Qin;ZHAO Aidi(School of Physical Science and Technology,ShanghaiTech University,Shanghai 201210,China)

机构地区：[1]上海科技大学物质科学与技术学院,上海201210

出　　处：《人工晶体学报》2023年第5期886-893,共8页Journal of Synthetic Crystals

基　　金：国家自然科学基金(22102101)。

摘　　要：α-MoO_(3)是一种典型的层状半导体过渡金属氧化物,其独特的电子结构和晶格结构使其近些年来被广泛研究。相比于体相α-MoO_(3),α-MoO_(3)薄膜因二维几何限制而具有优异的光学、电学和力学性质。然而,单层无缺陷的α-MoO_(3)薄膜的外延生长迄今尚未实现。本研究在超高真空条件下使用分子束外延技术,首次在高定向热解石墨(HOPG)上范德瓦耳斯外延制备了单层无缺陷的半导体α-MoO_(3)薄膜,并通过氢气还原的方法产生线型缺陷,使用扫描隧道显微镜研究了完整单层薄膜及缺陷处的形貌结构和表观能隙。结果表明:通过精确控制衬底温度可以在HOPG衬底上制备出高质量单层α-MoO_(3)薄膜;薄膜厚度和单胞大小均符合单层α-MoO_(3)特征,扫描隧道谱显示其表观能隙为1.7 eV;所生长薄膜的高质量可以通过衬底HOPG的摩尔纹进一步证实。通过引入氢气可以在薄膜表面获得与摩尔纹方向垂直的明亮线缺陷,缺陷处的局域表观能隙为0.4 eV,即在一个整体为宽表观能隙的半导体材料中间实现了局部的具有窄表观能隙的通道。α-MoO_(3)is a typical layered semiconductor transition metal oxide,and its unique electronic structure and lattice structure have made it widely studied in recent years.Compared with bulkα-MoO_(3),α-MoO_(3)film has excellent optical,electrical and mechanical properties due to its two-dimensional geometric limitations.However,the epitaxial growth of singlelayer defect-freeα-MoO_(3)film has not been realized so far.In this paper,molecular beam epitaxy was used in ultra-high vacuum,and a single-layer defect-free semiconductorα-MoO_(3)film was prepared by van der Waals epitaxial on highly oriented pyrolytic graphite(HOPG)for the first time,and linear defects were generated by hydrogen reduction.The microstructure and apparent energy gap of the defect-free single-layer film and the defect were studied by scanning tunneling microscope(STM).The results show that,high-quality single-layerα-MoO_(3)films can be prepared on HOPG substrates by accurately controlling the substrate temperature.The film thickness and cell size conform to the characteristics of single-layerα-MoO_(3),and the apparent energy gap of 1.7 eV is determined by the scanning tunnel spectrum.The high quality of the grown film can be further confirmed by the moire pattern on the substrate HOPG.By introducing hydrogen,bright line defects perpendicular to the moire pattern can be obtained on the surface of the film,and the local apparent energy gap of the line defects is 0.4 eV,that is,a narrowband semiconductor channel is realized inside a broadband semiconductor.

关 键 词：α-MoO_(3) 薄膜 高定向热解石墨 范德瓦耳斯外延 半导体 表观能隙 

分 类 号：O484.1[理学—固体物理]